Measuring device



F6118 1955 JONES 2,701,560

MEASURING DEVICE Filed April 5, 1952 2 Sheets-Sheet l 1 7591, .LW

Feb. 8, 1955 H, M JONES 7 2,701,560

MEASURING DEVICE Filed April 5, 1952 I 2 Sheets-Sheet 2 I z 1 5 2 United States Patent This invention relates to a method and apparatus for measuring metabolism rate and more particularly to such a method and apparatus wherein atmospheric air is breathed by the patient in a closed circuit during testing.

Many hospitals, institutions and privatepractioners offices are equipped with apparatus for determining the rate of consumption of oxygen by an individual for the purpose of certain diagnosis. Most of the. apparatus in use today provides a closed circuit from .which a patient obtains oxygen for breathing during determination of the metabolism rate. The circuit is designed to contain only oxygen and during the test no air is admitted into the circuit.

The presently used methods, of course, require the purchase and handling of bottles or other containers of oxygen as well as provision of means for injecting the oxygen into the testing equipment. conducted unless there is a supply of oxygen on hand and therefore the ability to perform a test is entirely dependent upon the supply.

The present invention provides a method of determining metabolism rate and an apparatus suitable for use in performing the method in which the patient breathes only atmospheric air in a closed circuit.

In general a tank or container is provided for containing a sufiicient quantity of air for a patient to breathe A test cannot be over a testing period without reducing the oxygen content of the trapped volume of air to a point below that which is safe for a person to breathe and remain conscious. A visible recordof the volume change in the air is recorded with relation to time thereby giving the rate of consumption of oxygen directly from the visible record.

An exemplary embodiment of the invention is shown in the accompanying drawings illustrating an apparatus suitable for carrying out the method of the invention and in which:

Fig. l is a vertical side elevational view partly in section of the apparatus; Fig. 1a is a fragmentary side view continuation of the breathing tubes shown in Fig.

1; Fig.2 is a substantially horizontal sectional view taken substantially along line 2-2 in Fig. 1; Fig. 3 is a front elevational view of the apparatus with the bottom portion partially cut away and taken substantially along line 3-3 in Fig. 1'; and Fig. 4 a fragmentary horizontal sectional view taken substantially along 44 in Fig. 1.

In Fig. 1 a metabolism testing device for performing the method to be described in detail is shown supported on a floor 10 by means of legs 11 on casters 12 which support a cabinet 13 enclosing most of the parts of the device. The cabinet is provided with side walls 14, a rear wall 15, front walls 16, a top 17 and a bottom 18. A hinged door 19 is provided in the front of the cabinet frame 13 and these walls enclose the interior space in which a portion of the breathing circuit is contained. The cabinet may be constructed of metal or wood either with a finish commensurate with hospital cleanliness.

A closed breathing circuit is provided to contain atmospheric air. A large tank 20 is supported within the cabinet 13 for containing a charge of air. This tank in the specific embodiment shown has a capacity of approximately 60 liters in which there is approximately 20 to 21% oxygen, thus providing approximately 12 liters of oxygen. An extraordinary large person will consume, at the most, approximately 3 liters of oxygen during a metabolism test and thus will reduce the oxygen content in the air of the circuit to not lower :than about 16%. A human individual can assimilate oxygen from air which contains as low as 14% before even the slightest symptoms. of losing consciousness. In any event the tank 20 and other parts of the circuit should have a capacity many times the lung capacity of the individual being tested and suflicient oxygen to permit the individual to assimilate oxygen without passing out during the test.

Means are provided for charging the tank 20 with atmospheric air including a sweep 21 attached to a center rod 22 having an eye 23 on its upper end reposing in a cappednipple 24 at the top of the tank. The sweep is provided with a rubber gasket closure 25 .at its bottom side adapted to seat on a bottom nipple 26 in the tank. When desiring to place a charge of fresh air in the tank, the cap 27 is removed from the upper nipple 24 and the sweep 21 is raised and lowered in the tank manually to clean out all air previously in the tank and to fill the tank with fresh air.

An expansible bellows 30 of rubber material is secured by one end 31 to the tank and by the other end 32 to the door 19 of the cabinet 13. An opening formed by a nipple 33 provides communication between the interior of the tank and bellows. A latch 34 holds the door 19 in alignment with the cabinet 13 when the apparatus is not in use. The previously mentioned capacity of the system includes the capacity of the bellows 3'0.

Breathing in the circuit is accomplished by means of a breathing tube 40 which may be connected with the interior .of the tank. A mouthpiece 41 is provided for placement in the mouth of the patient and the breathing is accomplished through an inhalation branch line 42 and an exhalation branch line 43. On the rear side of tank 20 is provided a narrow elongated passage 44 which connects with a plurality of nipples 45. This passage is connected with the tank through an opening 46 near the bottom thereof and all air passing into pas sage 44 is conducted into the bottom of the tank. The inhalations are carried through a nipple 47 near the top of the tank into the branch 42 of the breathing tube. The nipples are staggered in height along the tank to accommodate different bed heights and thus position the breathing tube at the correct elevation to reach a reclining patient. By means of passage 44 and the nipple 47, normal breathing of the patient circulates the air in the closed circuit. A convenient means of forming passage 44 may be seen 'in Fig. 4 wherein a plate 48 is welded as at 49 to the exterior of the tank 20 in spaced relation thereto.

The breathing tubes are connected with the tank by placing at least one of the tube branches 42 or 43 in communication with the upper nipple 47 and the other branch in communication with one of the other nipples 45. The inhalation branch 42 is provided with a check valve 50 which permits a passage of air into the tube and prevents reverse; movement of air. Likewise, the exhalation branch 43 is provided with a check valve 50 which has a reverse operation. Caps 52 are provided on the nipples not in use.

In performing a metabolism test the carbon dioxide of the exhalations are removed as well as the moisture from the breath. This is accomplished by means of a calcium chloride cartridge 53 placed in the exhalation branch 43 and a soda lime cartridge 54 between cartridge 53 and tank 20. These cartridges can be formed with threaded shanks for securing them together and for securing the soda lime cartridge to an adaptor 55 placed in one of the nipples.

In performing a test for a patient the door 19 on the front of cabinet is released by turning the catch 34 to inoperative position, whereupon the bellows 30 will be free to expand and contract with breathing fluctuations. The door is connected to a recording timer 58 by a link 59 which oscillates a stylus 60 over the face of a recording sheet 61. The recording apparatus is supported by a bracket 64 secured to the cabinet 13 on either side of the hinged door 19. The timing clock 62 travels the sheet 61 downwardly at a predetermined rate so that the oscillations of the stylus 60 caused by breathing fluctuations will make a visible graph on the sheet. Obviously as the patient continues to breathe in the closed circuit, the

lung capacity can produce a volume of the air in the circuit will decrease and since carbon dioxide is removed from exhalations, the decrease is only caused by consumption of oxygen.

The particular means used for connecting the bellows with the recording apparatus includes the rocker arm 65 pivotally secured to the outer endof link 59. This link is in'the shape of a T and the crosspiece which extends substantially vertically is provided with a number of openings for receiving a thumbscrew 66 which will extend into a vertical slot 67 in the rocker 65. By varying the position of the thumbscrew 66, a given linear movement of the bellows can provide a varying magnitude of movement in the stylus 60. Thus a patient with a small graph having oscillation of a magnitude equal to a graph produced by a person of larger lung capacity by varying the magnitude of stylus oscillations as compared to the oscillation of the bellows.

It has been found advisable to enclose the tank 20 in the cabinet 13 in a manner to reduce the amount of free air circulation about the tank to a minimum. In the present device the cabinet encloses the tank and free air about the exterior thereof is substantially dead air even during the movements of the hinged door 19. It is also desirable to insulate the metal nipples 45 and 47 by providing a rubber or synthetic covering between. the nipples and the metal parts of the cabinet. As a further means of reducing any change of temperature from effect of room temperature changes during the few minutes required for the test, the tank 20 is closely wrapped with a blanket of insulating felt 28. The warmth of the breath itself causes no appreciable change in temperature of the air volumes in tank 20. Inasmuch as a change in temperature in a volume of air such as is trapped in the tank 20 would be indicated in the amount of expansion of the bellows, it is important that no change occur during the test. Ordinarily the temperature of the air inside the tank will be approximately the same as that of the room in which the test is being conducted.

In performing the method of the present invention to determine rate of consumption of oxygen, the tank 20 is filled with sufficient air from the room in which the test is to be conducted by sweeping foul air out of the tank and replacing it with fresh air. The breathing tube 40 is connected with the interior of the tank and the mouthpiece fitted in the patients mouth. The patient is permitted to breathe in the closed circuit thus causing the bellows 30 to expand and contract, making a visible record of the volume changes in the circuit on the recording sheet 61. The test is conducted for a period of time, for

example six to ten minutes, in order to obtain a graph of sufficient length to indicate the rate of consumption of oxygen. At the end of the test period the patient may be disconnected from the closed circuit and the recorded visual record of changes in volume of the confined air will give the correct metabolism rate when atmospheric temperature, barometic pressure and aqueous tension are taken into consideration. During the test, carbon dioxide and moisture are removed from the patients exhalations so that the only decrease in volume of the air is caused by consumption of oxygen. By weighing the soda lime cartridge before and after a breathing period, the ratio of Oz consumed to the CO2 eliminated is easily computed to give the patients respiratory quotient which is of value in diagnosing certain conditions, thus providing a means for obtaining this factor. The device may be used for obtaining rate of consumption of oxygen only, 1n which case the calcium chloride cartridge is not needed.

While I have shown and described certain embodimentsof myinvention, it is to be understood that 'it is capable of many modifications. Changes, therefore, in the construction and arrangement may be made without departing from the spirit and scope of the invention as disclosed in the appended claims.

I claim:

1. An apparatus for measuring the rate of consumption of oxygen, comprising: a tank adapted to contain atmospheric air; insulating means enclosing the tank; an expansible bellows having one end attached to the tank; means supporting the other end of the bellows for movement relative to the tank; means providing communication between the interior of the bellows and the interior of the tank; a breathing tube communicating with the interior of the tank; volume change recording means connected to the movable end of the bellows and means forming an opening in the top and bottom of the tank and a sweep member movable lengthwise of the tank to sweep air therefrom for emptying and filling the tank with fresh air.

2. An apparatus for measuring the rate of consumption of oxygen, comprising: a tank adapted to contain atmospheric air; an expansible bellows having one end attached to the tank; means supporting the other end of the bellows for movement relative to the tank; means providing communication between the interior of the bellows and the interior of the tank; a breathing tube communicating with the interior of the tank; a volume change recording means connected to the movable end of the bellows and means forming an opening in the tank and a sweep member movable lengthwise of the tank to sweep air therefrom for emptying and filling the tank with fresh air.

3. Apparatus as specified in claim 2 in which a plurality of vertically spaced breathing tube connections are provided with said tank, the upper connection having direct communication with the tank and the other connections communicating with a downwardly extending passage having communication with the bottom portion of the tank.

4. An apparatus for measuring the rate of consumption of oxygen from a confined mass of atmospheric air, comprising: a tank adapted to contain said atmospheric air; an expansible member communicating with the tank and having one end connected to the tank and the other end movable relative to the tank; breathing tube means communicating with the tank, said tube means having two parts, one part having direct communication with the upper portion of the tank; means forming an upright passage in the tank and opening only into the lower portion of the tank, the other part of said breathing tube means communicating with an upper portion of said upright passage; a check valve in each breathing tube part so that breathing in the tube means may circulate air in the tank; and volume change recording means connected to the movable end of the expansible member.

5. Apparatus as specified in claim 4 wherein said upright passage is formed by a plate member extending upwardly along the tank wall and having edges joined to the tank wall to form said passage between the plate and tank Wall.

References Cited in the file of this patent UNITED STATES PATENTS 1,550,335 Benedict et al Aug. 18, l925 2,180,057 Jones Nov. 14, 1939 2,228,983 Bloomheart Jan. 14, 1941 

